Solar cell

Abstract

A solar cell, comprising: a metal substrate having an insulating anodic oxidation film; and a photoelectric conversion layer provided on the metal substrate, whereon the anodic oxidation film has a surface roughness of 0.5 nm to 2 μm and the photoelectric conversion layer comprises a chalcopyrite semiconductor material having a band gap of 1.3 eV to 1.5 eV.

Description

TECHNICAL FIELD[0001]The present invention relates to thin-film solar batteries and more specifically to a lightweight, highly flexible thin-film solar cell produced with an anodized aluminum substrate.BACKGROUND ART[0002]Glass substrates are mainly used as thin-film solar cell substrates. However, a glass substrate is fragile and must be treated with considerable care and its lack of flexibility limits the scope of the application. Recently, solar batteries have attracted much attention as power supply sources to buildings including homes. It is inevitable to upsize solar batteries in order to ensure sufficient electric power to supply, and there has been a demand for a more lightweight substrate that should contribute to production of solar batteries with larger areas.[0003]However, a glass substrate would be even more fragile if it is thinned for reduction in weight. Therefore, there has been a demand for development of a less fragile and more flexible substrate material that can...

AI Technical Summary

Benefits of technology

[0056]Ti is generally added in the form of an intermetallic compound with Al or in the form of TiB2. In order to enhance the grain refining effect, however, Ti is preferably added in the form of an Al—Ti alloy or an Al—B—Ti alloy. When Ti is added in the form of an Al—B—Ti alloy, a very trace amount of boron (B) is also added to the aluminum alloy, which does not reduce the effect of the invention.

[0057]When the aluminum sheet containing each of the above different elements in the above content range is used, large pits are uniformly formed in the electrolytic surface roughening treatment described below, so that the adhesion of the aluminum sheet is favorable in the resulting solar cell.

[0058]The balance of the aluminum sheet is preferably composed of Al and inevitable impurities. Most of the inevitable impurities are contained in the Al ingot. For example, when contained in an Al ingot with a purity of 99.7%, the inevitable impurities do not reduce the effect of the invention. For example, the inevitable impurities may be contained in amounts as described in L. F. Mondolfo, “Aluminum Alloys: Structure and Properties” (1976).

[0059]Examples of inevitable impurities contained in aluminum alloys include Mg, Mn, Zn, and Cr, each of which may be contained in an amount of 0.05% by weight or lower. Any additional element other than these elements may also be contained in an amount known in the art.

[0060]The aluminum sheet for use in an embodiment of the invention may be produced by a process including subjecting the above raw material to casting by a ordinary method, subjecting the cast product to an appropriate rolling process and appropriate heat treatment, for example, to produce a 0.1 to 0.7 mm thick product, and optionally performing a flatness correcting process. The thickness may be changed as appropriate.

[0061]Examples of methods that may be used to produce the aluminum sheet include a DC casting method, a method of performing DC casting, excluding soaking and / or annealing, and a continuous casting method.

Problems solved by technology

However, a glass substrate is fragile and must be treated with considerable care and its lack of flexibility limits the scope of the application.

However, a glass substrate would be even more fragile if it is thinned for reduction in weight.

If a metal is used as such a substrate material, its insulation from a solar cell material arranged thereon is difficult, while a resin substrate cannot withstand a high temperature exceeding 400° C. that is necessary to form a solar cell.

Furthermore, in a chalcopyrite material with higher light absorption efficiency, sufficient light cannot be confined, and incoming sunlight is not used effectively.

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